Experience of applicant's assignee with sheet feeders of the type disclosed in U.S. Pat. No. 3,522,943 has shown that collators, and in particular inserters, require some modifications and improvements in order to adapt them for efficient operation with such a signature or sheet feeder, or with the sheet feeder of applicant's co-pending application heretofore referred to.
Signature or sheet feeders as disclosed in the patent are particularly designed for use with a collator having hoppers in which the sheets or signatures are horizontal or substantially so. There are prior art flat gatherers which have hoppers in which the sheets are horizontal, but the only inserter having such a hopper is Mueller U.S. Pat. No. 3,199,862. Prior art collators may employ lifter hooks as part of their stack control, but any such lifter hooks known to applicant have been driven by mechanisms which are subject to excessive wear and which are also extremely noisy when used in a high speed collator.